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. 2018 Jan:64:19-29.
doi: 10.1016/j.neuro.2017.05.010. Epub 2017 Jun 3.

Association of MRI T1 relaxation time with neuropsychological test performance in manganese- exposed welders

R M Bowler  1 , C-L Yeh  2 , S W Adams  3 , E J Ward  4 , R E Ma  2 , S Dharmadhikari  5 , S A Snyder  6 , S E Zauber  7 , C W Wright  3 , U Dydak  8
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Association of MRI T1 relaxation time with neuropsychological test performance in manganese- exposed welders

R M Bowler et al. Neurotoxicology. 2018 Jan.

Abstract

This study examines the results of neuropsychological testing of 26 active welders and 17 similar controls and their relationship to welders' shortened MRI T1 relaxation time, indicative of increased brain manganese (Mn) accumulation. Welders were exposed to Mn for an average duration of 12.25 years to average levels of Mn in air of 0.11±0.05mg/m3. Welders scored significantly worse than controls on Fruit Naming and the Parallel Lines test of graphomotor tremor. Welders had shorter MRI T1 relaxation times than controls in the globus pallidus, substantia nigra, caudate nucleus, and the anterior prefrontal lobe. 63% of the variation in MRI T1 relaxation times was accounted for by exposure group. In welders, lower relaxation times in the caudate nucleus and substantia nigra were associated with lower neuropsychological test performance on tests of verbal fluency (Fruit Naming), verbal learning, memory, and perseveration (WHO-UCLA AVLT). Results indicate that verbal function may be one of the first cognitive domains affected by brain Mn deposition in welders as reflected by MRI T1 relaxation times.

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Figures

Figure 1
Figure 1
Regions of Interest (ROIs) displayed on T1-weighted images of a control (a) and a welder (b). Color of the ROI: blue for substantia nigra, red for caudate, green for globus pallidus, and yellow for anterior prefrontal lobe. Slight T1 hyperintensities can be discerned in this welder.
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